Inflammatory myofibroblastic tumours (IMTs) are clinicopathologically distinctive but biologically controversial entities, which have been described in the lungs, abdomen, retroperitoneum, and extremities, but rarely affect the head and neck region. IMT usually follows a benign clinical course after radical excision, but invasive, locally recurrent, and metastatic forms of abdominal and mediastinal IMT have also been described. This report describes a case of IMT of the paranasal sinuses with a fatal outcome. A 22 year old woman was admitted to hospital as a result of epistaxis. Computed tomography scan and magnetic resonance imaging showed an expansive process in the paranasal sinuses, extending into the nasal cavity, orbita, and endocranium. The tumour progressed despite several surgical procedures. Radiotherapy, corticosteroids, and chemotherapy were unsuccessful, and the patient died four years after diagnosis, as a result of extensive intracranial spread of the tumour. This is the first known case of an IMT of the head and neck region with a fatal outcome. It shows that the aggressive behaviour of IMTs is not limited to abdominal and mediastinal locations, and supports recent observations that at least a subset of IMTs represents true neoplasia rather than reactive myofibroblastic proliferation.